mercredi 7 octobre 2015

Exoplanet Anniversary: From Zero to Thousands in 20 Years

NASA - Kepler Space Telescope Mission patch.

October 7, 2015

Image above: This year we celebrate the discovery of 51 Pegasi b in October, 1995. This giant planet is about half the size of Jupiter and orbits its star in about four days. '51 Peg' helped launch a whole new field of exploration. Image credits: NASA/JPL-Caltech.

October 6 marks the 20th anniversary of the first discovery of a planet orbiting a sun-like, or "normal," star beyond our solar system. The planet, called 51 Pegasi b, belongs to a class of planets now known as exoplanets. Since that momentous discovery, thousands more exoplanets have been found in our galaxy.

As of today, there are more than 1,800 confirmed exoplanets. More than 1,000 of these were discovered by NASA's Kepler mission, breaking wide open the field of exoplanet science. Kepler has even identified some planets with Earth-like traits, such as Kepler-452b, a near-Earth-size planet found in the habitable zone of a sun-like star. The habitable zone is the region around a star where temperatures are just right for one of life's essential ingredients -- water -- to pool on a planet's surface.

Poster above: Discovered in October 2013 using direct imaging, PSO J318.5-22 belongs to a special class of planets called rogue, or free-floating, planets. Wandering alone in the galaxy, they do not orbit a parent star. Not much is known about how these planets come to exist, but scientists theorize that they may be either failed stars or planets ejected from very young systems after an encounter with another planet. These rogue planets glow faintly from the heat of their formation. Once they cool down, they will be dancing in the dark. Poster Credits: NASA/JPL.

Experience the Gravity of a Super Earth

Poster above: Twice as big in volume as the Earth, HD 40307g straddles the line between "Super-Earth" and "mini-Neptune" and scientists aren't sure if it has a rocky surface or one that's buried beneath thick layers of gas and ice. One thing is certain though: at eight time the Earth's mass, its gravitational pull is much, much stronger. Poster Credits: NASA/JPL.

Relax on Kepler-16b - Where your shadow always has company

Poster above: Like Luke Skywalker's planet "Tatooine" in Star Wars, Kepler-16b orbits a pair of stars. Depicted here as a terrestrial planet, Kepler-16b might also be a gas giant like Saturn. Prospects for life on this unusual world aren't good, as it has a temperature similar to that of dry ice. But the discovery indicates that the movie's iconic double-sunset is anything but science fiction. Poster Credits: NASA/JPL.

Kepler-186 f - Where the Grass is Always Redder

Poster above: Kepler-186f is the first Earth-size planet discovered in the potentially 'habitable zone' around another star, where liquid water could exist on the planet's surface. Its star is much cooler and redder than our Sun. If plant life does exist on a planet like Kepler-186f, its photosynthesis could have been influenced by the star's red-wavelength photons, making for a color palette that's very different than the greens on Earth. This discovery was made by Kepler, NASA's planet hunting telescope. Poster Credits: NASA/JPL.

NASA's Ames Research Center, Moffett Field, California, manages the Kepler and K2 missions for NASA's Science Mission Directorate. NASA's Jet Propulsion Laboratory in Pasadena, California, managed Kepler mission development. Ball Aerospace & Technologies Corporation operates the flight system with support from the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder.